1. Field of the Invention
The present invention relates, in general, to the packaging of products in flexible bags or containers and, more particularly, relates to an improved apparatus for bagging a product in a deformable bag and sealing it therein.
2. State of the Art
The distribution of perishable items, such as produce, as well as non-perishable products in thin, usually transparent, plastic bags has become widespread over the years. Plastic deformable bags have considerable strength and, further, have storage capabilities which enhance product quality and extend useful life. Mass production of these bags through automated machines has made them particularly desirable, feasible and cost effective.
Prior art FIG. 1 schematically illustrates a typical bagging apparatus 10. The apparatus 10 includes a roll of plastic 12 which is folded at one end 14. The roll of plastic 12 is located with its axis 16 horizontal and is fed through several feed rollers 18, 20, 22 until it assumes a vertical position. A spreading device 24 is arranged to open the free end 15 of the folded plastic so that a product may be placed between the folded plastic film. Prior art FIG. 2 schematically illustrates a sealing device 28. The sealing device would be located beneath the spreading device 24 in FIG. 1. The sealing device 28 generally includes an L-shaped heated bar 30 and an L-shaped resilient sealing surface 32. The two L-shaped members 30, 32 are slideably mounted on rods 34, 36 so that they may be moved together and apart. As shown in prior art FIGS. 3A and 3B, the heated bar 30 is movable within a clamp 38 and has a rounded end 39. When the L-shaped members are brought together, the clamp 38 holds the plastic sheet 12 against the sealing surface 32 and the heated bar 30 moves forward against the plastic to heat seal it and sever it from the roll of plastic. The sealing and severing locations are illustrated at 31 and 33 in FIG. 1. After sealing, a finished bag 40 is severed from the roll of plastic. A small strip of plastic 42 is left attached to the roll and is taken up by a trim spool 44.
The prior art bagging apparatus has several disadvantages. First, the product must enter the apparatus horizontally between the spreading apparatus and rollers. Second, it is difficult to alter the size of the bags to accommodate different sized products. Third, in order to prevent ragged uneven seals, the heated bar must be coated with a non-stick material. Nevertheless, repeated cycling causes some residual buildup of plastic on the heated bar since it must penetrate the plastic to sever the bag from the roll. The abrasion on the bar by the act of penetrating the plastic causes the non-stick coating to wear off.
It is therefore an object of the invention to provide a bagging apparatus which allows product loading from either above or the side.
It is also an object of the invention to provide a bagging apparatus which is easily adjustable to make a wide variety of different sized bags
It is another object of the invention to provide a bagging apparatus with an improved sealing and severing system.
In accord with these objects which will be discussed in detail below, the vertical bagging apparatus of the present invention includes a vertically mounted spool for dispensing a roll of centerfold plastic film with the fold in the upper position. A pair of vertical metering rollers are mounted adjacent to the spool for advancing the film from the spool. An adjustable generally inverted-V-shaped film inverted is mounted downstream from the metering rollers. A sealing and severing system is located beneath the film invertor and a trim spool is located beneath the sealing and severing system. The film invertor turns-the film inside out, relocating the fold from the horizontal axis to the vertical axis. The film invertor also causes the open end of the folded film to be accessible from either above or the side. The film invertor is adjustable by raising and lowering the apex of the inverted-V which relocates the horizontal location of the fold in the film. According to a presently preferred embodiment, the film invertor is made from flexible wire and the free ends of the wire are attached to a takeup shaft. According to the invention, the sealing and severing system includes a flat faced heated bar and a sharp contoured compliant sealing surface. This system provides sealing and severing without buildup of plastic material on the heated bar because the severing is actually performed by the cool sealing surface rather than by the heated bar. The sealing and severing system is preferably arranged on gear coupled double pivot arms and is actuated by a double piston arrangement. Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.